:root {
  --color-text: #1d2d35;
  --color-link-active: #0a58ca;
  --color-link-hover: #0a58ca;
  --type-small: 1.25rem;
  --type-medium: 1.4rem;
  --type-large: 2rem;
  --type-xlarge: 2.5rem;
}

body {
  font-family: "Georgia", serif;
  margin: 0;
  background: #ffffff;
  color: var(--color-text);
  line-height: 1.6;
  font-size: var(--type-medium);
}

.container {
  display: flex;
  min-height: 100vh;
  flex-direction: row; /* <-- force side-by-side layout by default */
}

.content {
  margin: 0 auto 0 0;
  max-width: 60vw;
  padding: 4rem 2rem;
}

h1,
h2,
h3 {
  font-family: "Lato", sans-serif;
  font-weight: bold;
  color: var(--color-text);
  line-height: 1.4;
  margin-bottom: 1rem;
}

h1 {
  font-size: var(--type-xlarge);
  margin-top: 2.5rem;
}

h2 {
  font-size: var(--type-medium);
  margin-top: 0.5rem;
}

h3 {
  font-size: 1.25rem;
}

p {
  margin: 1rem 0;
  font-size: var(--type-medium);
  color: var(--color-text);
}

code {
  background: #f0f0f0;
  padding: 0.2rem 0.4rem;
  border-radius: 4px;
  font-size: 90%;
}

a {
  text-decoration: none;
  color: var(--color-text);
}

a:hover {
  text-decoration: underline;
  color: var(--color-link-hover);
}

.sidebar {
  width: 20vw;
  padding: 4rem;
  position: sticky;
  top: 0;
  height: 100vh;
}

.sidebar .logo {
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.sidebar .logo svg {
  width: 5rem;
  height: 5rem;
  fill: var(--color-link-hover);
  display: block;
}

.sidebar h1 {
  margin: 0.5rem 0;
}

.sidebar h1 a {
  text-decoration: none;
  font-family: "Lato", sans-serif;
  font-size: var(--type-medium);
  font-weight: bold;
  color: var(--color-text);
}

.sidebar h1 a.active {
  color: var(--color-link-active);
}

.sidebar nav ul {
  list-style: none;
  padding: 0;
  margin-top: 0.5rem;
}

.sidebar nav li {
  margin-bottom: 0.5rem;
}

.sidebar nav a {
  font-family: "Lato", sans-serif;
  text-decoration: none;
  font-size: var(--type-small);
  color: var(--color-text);
  display: block;
}

.sidebar nav a:hover {
  color: var(--color-link-hover);
}

.sidebar nav a.active {
  color: var(--color-link-active);
}

footer {
  text-align: left;
  padding: 2rem 0;
  margin-top: 2rem;
  font-size: var(--type-small);
  font-family: "Lato", sans-serif;
  border-top: 1px solid var(--color-text);
}

.highlight {
  border: 4px solid var(--color-link-hover);
  border-radius: 0.5em;
  padding: 0.5rem calc(1rem - 4px);
  margin: 1.5rem -1rem;
  font-size: var(--type-medium);
  line-height: 1.75;
}

.highlight p {
  margin: 0;
}

.chapter-list {
  list-style: none;
  padding: 0;
  margin: 2rem 0;
}

.chapter-list li {
  margin-bottom: 1rem;
}

.chapter-list a {
  font-size: var(--type-medium);
  font-family: "Lato", sans-serif;

  color: var(--color-link);
  text-decoration: none;
}

.chapter-list a:hover {
  color: var(--color-link-hover);
}

.next-link {
  font-family: "Lato", sans-serif;
  color: var(--color-link);
  text-decoration: none;
}

.next-link:hover {
  color: var(--color-link-hover);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 2rem;
  margin-left: auto;
  cursor: pointer;
  color: var(--color-text);
}

@media (max-width: 991px) {
  .container {
    display: flex;
    min-height: 100vh;
    flex-direction: column; /* <-- force side-by-side layout by default */
  }

  .sidebar {
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    padding: 0;
    height: auto;
    position: static;
    width: 100%;
    border-bottom: 1px solid var(--color-link-hover);
    border-right: none;
  }

  .sidebar .logo {
    display: flex;
    flex-direction: row;
    align-items: center; /* This vertically centers children */
    flex-wrap: wrap;
    flex-grow: 1;
    padding: 1rem 3rem;
    margin: 0;
    gap: 1rem;
  }

  .sidebar h1 a {
    margin: 0;
  }

  .nav-toggle {
    display: block;
  }

  nav#sidebar-nav {
    width: 100%;
    display: none;
    flex-direction: column;
    margin-top: 1rem;
  }

  nav#sidebar-nav.open {
    display: flex;
  }

  .sidebar nav ul {
    flex-direction: column;
    gap: 0.5rem;
    margin: 0;
  }

  .sidebar nav li {
    margin: 0;
  }
  .content {
    padding: 2rem 1.5rem;
    max-width: 80vw;
    margin: 0 auto;
  }
}

.levels {
  display: grid;
  gap: 1rem;
  font-family: "Lato", sans-serif;
}

.level {
  padding: 1rem;
}

.task {
  margin-bottom: 0.5rem;
}

.task-title {
  display: block;
  background: none;
  border: none;
  font-size: 1.1rem;
  color: var(--color-link);
  text-align: left;
  cursor: pointer;
  padding: 0.25rem 0;
}

.task-title:hover {
  color: var(--color-link-hover);
}

.task-details {
  margin-top: 0.5rem;
  line-height: 1.4;
  font-size: 1.1rem;
  font-family: "Lato", sans-serif;
}